diff --git a/include/linux/usb.h b/include/linux/usb.h
index 27a4e16..69d8457 100644
--- a/include/linux/usb.h
+++ b/include/linux/usb.h
@@ -1073,6 +1073,7 @@
  *	which the host controller driver should use in preference to the
  *	transfer_buffer.
  * @sg: scatter gather buffer list
+ * @num_mapped_sgs: (internal) number of mapped sg entries
  * @num_sgs: number of entries in the sg list
  * @transfer_buffer_length: How big is transfer_buffer.  The transfer may
  *	be broken up into chunks according to the current maximum packet